Receiving-telephone



(N0 Model.) I

J. A. MALONEY.

- RECEIVING TELEPHONE N0. 274,352. H Patented Mar.20.1883. v

UNITED STATES PATENT JAMES A. hIAIiONEY, OF \VASHINGTON, DISTRICT OFCOLUMBIA, ASSIGNOR TO S. H. CARNEY, TRUSTEE, OF NEW YORK.

RECEIVING-TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 274,352, dated March20, 1883.

Application filed January .2, 1883. (No model.)

To all whom it may concern Be it known that I, JAMES A. MALONEY, ofWashington city, in the District of Columbia, have invented certain newand useful Improvemerits in Receiving-Telephones, of which the followingis a specification.

My invention has for its object to increase the efficiency ofreceiving-telephones. 1n the instrument devised by me there is combinedto with the diaphragm an electro-rnagnet which is in the line-circuit,and is provided with a tubular longitudinally-slit soft-iron 'core. Inother words, the core of the electro-inagnet, instead of being solid, isa hollow cylindrical shell, which is slit lengthwise on one side fromend to end, the contiguous edges bounding the slit being out of contactwith one another. A core having these characteristics acts to reproducethe voice with great distinctness, and renders the instrument sensitiveand very efficient. Inasmuch as a soft-iron core elon gates whenmagnetized, and variations in magnetization or alternate magnetizationand demagnetization will result in corresponding variations in itslength, and, further, as it is reasonable to suppose that increase inits length is accompanied by corresponding decrease in itscross-section, and vice versa,it is not improbable that these changes inthe tubular core are 0 permitted more readily and quickly to take placeby slitting it lengthwise; but, however this may be, the fact remainsthat a core possessing the characteristics above stated is very muchmore efficient than and produces results that cannot be obtained by theemployment under similar conditions of either an unslit tube or a solidcore. In my receiving-instrument the electro-magnet is intermediatebetween the diaphragm and the ear opening or trumpet, and the tubularcore thus acts in a measure as a resonator-tube. In practice I havefound that the etficiency of the instrument is enhanced materially byforming in the tubular core, in addition to the continuous 5longitudinal slit, a series of slits extending lengthwise from each endof the core toward its center in length-say about one-third of thelength of the core, more or less. This construction allows the core tobe polarized and depolarized more rapidly than otherwise would be thecase.

The nature of my invention and the manner in which the same is ormay becarried into effect will be readily understood by reference to theaccompanying drawings, in which- 5 Figure 1 is a longitudinal centralsection of the receiving-telephone. Fig. 2 is a section on line 00 m,Fig. 1. Fig. 3 is a section on line yy, Fig. 1. Fig. t is a perspectiveview of the instrument. Fig. 5 is a perspective view of the diaphragmand its rubber washer. Fig. 6 is a side elevation of the electro-magnei.Fig. 7 is a perspective view of the tubular longitudinally-slit core.Figs. 8 and 9 represent a modification ofthe core. Fig.8 shows in planthe 6 flat metal sheet, and Fig. 9 shows in perspective the core made bybending the sheet into cylindrical form.

The case of the instrument is made of nonconducting material in twoparts, A B,'screwed together, and holding between them the me-. tallicdiaphragm G and its rubber washer (r. The front part, A, has the openingto which the ear is applied, and which I term the eartrumpet, letteredI), and it is made hollow to 7 receive the electromagnet D. The latterconsists of a coil of insulated wire wound on the wooden spool or bobbin0 in the usual way, the coil being electrically connected to linethrough the binding-posts d c, with which its two ends are respectivelyconnected, as indicated by dotted lines 1 and 2, Fig. 2. Within thebobbin is the tubular soft-iron core E, which, as shown in Fig. 7, hasthe form of a cylindrical shell longitudinally slit on one side from endto end, as indicated at f. In Fig. l the inner end of the core, for thepurpose of showing the parts more plainly, is represented as separatedby quite a space from the diaphragm. In practice, however, it is set upconsiderably nearer to, and, in fact, just out of contact with, thediaphragm, in which adjusted position it is maintained by suitablemeans.

The results obtained by me from the forego- 9 5 ing-describedconstruction and arrangement of parts have been already stated, and neednot besrepeated here. 1

In the modification represented in Figs. 8 and 9 the metal sheet fromwhich the core is made is preliminarily divided at its ends into anumber of teeth or narrow strips,'g, by a series of slits, which extendfrom each end for about one-third the length of the sheet. The length ofthe teeth may be Varied; but I find in practice than when they are madeof the length stated I obtain on the whole the best results. The sheetthus preliminarily formed is bent or rolled up into the form of a tube,as indicated in Fig. 9, and in this way a tubular core is producedhaving, as in the other instance, the longitudinal slitf, but havingalso, in addition, ends composed of strips g. This core is to beadjusted and used in the same manner as the core shown in theotherfigures. Having described my improvements and the best way now known tome of carrying the same into effect, what I claim therein as new and ofmy own invention is- 1. In a receiving-telephone, the combina' tion,with the diaphragm, of an electromagnet provided with a tubularlongitudinally-split soft-iron core, substantially as and for the pur- 25 poses hereinbefore set forth.

2. In a receiving-telephone, the combination,with the diaphragm and theear-trumpet, of an intermediate electro-magnet provided with atubularlol'lgitudinally-split soft-iron 0 core, which constitutes thecommunicating passage from the diaphragm to the ear-trumpet,substantially as hereinbefore set forth. I

3. The intermediate electro-magnet, having its coil electricallyconnected to line and pro- 5 vided with a tubular longitudinally-splitsoftiron core, in combination with the diaphragm and the ear-trumpet,substantially as set forth.

4. The electro-magnet core E, consisting of a soft-iron cylindricalshell, having the longi= 4o tudinal slitfand divided ends 9,substantially as and for the purposes hereinbefore set forth.

In testimony whereofI have hereunto set my hand this 2d day of January,1883.

JAMES A. MALONEY.

Witnesses:

EWELL A. DIcK, J. WALTER BLANDFQRD.

